diff --git a/.devcontainer/Dockerfile b/.devcontainer/Dockerfile
new file mode 100644
index 0000000000..3076a7fd25
--- /dev/null
+++ b/.devcontainer/Dockerfile
@@ -0,0 +1,13 @@
+FROM mcr.microsoft.com/devcontainers/javascript-node:22
+
+# pnpm is pre-installed in the devcontainer image; ensure correct version
+RUN corepack enable && corepack prepare pnpm@latest --activate
+
+# mise for runtime management
+RUN curl https://mise.run | sh && \
+    echo 'eval "$(~/.local/bin/mise activate bash)"' >> /home/node/.bashrc
+
+# System dependencies for Synapse (uses Docker) and node-gyp
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    build-essential \
+    && rm -rf /var/lib/apt/lists/*
diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
new file mode 100644
index 0000000000..812f835598
--- /dev/null
+++ b/.devcontainer/devcontainer.json
@@ -0,0 +1,46 @@
+{
+  "name": "Boxel PR Review",
+  "dockerComposeFile": "docker-compose.yml",
+  "service": "app",
+  "workspaceFolder": "/workspaces/boxel",
+
+  "features": {
+    "ghcr.io/devcontainers/features/docker-in-docker:2": {
+      "dockerDashComposeVersion": "v2"
+    },
+    "ghcr.io/devcontainers/features/python:1": {
+      "version": "3.11"
+    },
+    "ghcr.io/devcontainers/features/github-cli:1": {}
+  },
+
+  "forwardPorts": [4201, 4206, 8008],
+  "portsAttributes": {
+    "4201": { "label": "Realm Server", "onAutoForward": "silent" },
+    "4206": { "label": "Icons Server", "onAutoForward": "silent" },
+    "8008": { "label": "Matrix/Synapse", "onAutoForward": "silent" }
+  },
+
+  "postCreateCommand": "bash .devcontainer/setup.sh",
+  "postStartCommand": "bash .devcontainer/start-services.sh",
+
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "cardstack.boxel-tools",
+        "dbaeumer.vscode-eslint",
+        "esbenp.prettier-vscode",
+        "typed-ember.glint-vscode"
+      ],
+      "settings": {
+        "terminal.integrated.defaultProfile.linux": "bash"
+      }
+    }
+  },
+
+  "hostRequirements": {
+    "cpus": 4,
+    "memory": "8gb",
+    "storage": "64gb"
+  }
+}
diff --git a/.devcontainer/docker-compose.yml b/.devcontainer/docker-compose.yml
new file mode 100644
index 0000000000..cea942af2a
--- /dev/null
+++ b/.devcontainer/docker-compose.yml
@@ -0,0 +1,33 @@
+services:
+  app:
+    build:
+      context: ..
+      dockerfile: .devcontainer/Dockerfile
+    volumes:
+      - ..:/workspaces/boxel:cached
+    command: sleep infinity
+    environment:
+      - PGHOST=postgres
+      - PGPORT=5432
+      - PGUSER=postgres
+      - PGDATABASE=boxel
+      - NODE_NO_WARNINGS=1
+    depends_on:
+      postgres:
+        condition: service_healthy
+
+  postgres:
+    image: postgres:16.3
+    restart: unless-stopped
+    environment:
+      POSTGRES_HOST_AUTH_METHOD: trust
+    volumes:
+      - pgdata:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD", "pg_isready", "-U", "postgres"]
+      interval: 5s
+      timeout: 3s
+      retries: 5
+
+volumes:
+  pgdata:
diff --git a/.devcontainer/setup.sh b/.devcontainer/setup.sh
new file mode 100755
index 0000000000..f01ee9b48e
--- /dev/null
+++ b/.devcontainer/setup.sh
@@ -0,0 +1,18 @@
+#!/bin/bash
+# One-time setup after the container is created.
+# Runs during Codespace build (or prebuild) — keep it idempotent.
+# The host app is NOT built here; it's deployed via GitHub Actions.
+set -euo pipefail
+
+echo "==> Installing dependencies..."
+pnpm install --frozen-lockfile
+
+echo "==> Running database migrations..."
+cd packages/postgres
+PGHOST="${PGHOST:-postgres}" PGPORT="${PGPORT:-5432}" pnpm migrate up
+cd /workspaces/boxel
+
+echo "==> Setting up skills realm..."
+pnpm --dir=packages/skills-realm skills:setup
+
+echo "==> Setup complete. Backend services will start automatically."
diff --git a/.devcontainer/start-services.sh b/.devcontainer/start-services.sh
new file mode 100755
index 0000000000..09166c9875
--- /dev/null
+++ b/.devcontainer/start-services.sh
@@ -0,0 +1,126 @@
+#!/bin/bash
+# Start backend services for PR review in Codespaces.
+# The host app is NOT built here — a GitHub Actions workflow builds and
+# deploys it to S3 with URLs pointing back at this Codespace.
+set -euo pipefail
+
+cd /workspaces/boxel
+
+CODESPACE_NAME="${CODESPACE_NAME:?CODESPACE_NAME must be set}"
+GITHUB_CODESPACES_PORT_FORWARDING_DOMAIN="${GITHUB_CODESPACES_PORT_FORWARDING_DOMAIN:-app.github.dev}"
+
+# Derived Codespace URLs for forwarded ports
+export REALM_SERVER_URL="https://${CODESPACE_NAME}-4201.${GITHUB_CODESPACES_PORT_FORWARDING_DOMAIN}"
+export MATRIX_URL="https://${CODESPACE_NAME}-8008.${GITHUB_CODESPACES_PORT_FORWARDING_DOMAIN}"
+export ICONS_URL="https://${CODESPACE_NAME}-4206.${GITHUB_CODESPACES_PORT_FORWARDING_DOMAIN}"
+
+# Common env vars for realm-server processes
+export NODE_ENV=development
+export NODE_NO_WARNINGS=1
+export PGHOST="${PGHOST:-postgres}"
+export PGPORT="${PGPORT:-5432}"
+export PGDATABASE="${PGDATABASE:-boxel}"
+export LOG_LEVELS='*=info'
+export REALM_SERVER_SECRET_SEED="mum's the word"
+export REALM_SECRET_SEED="shhh! it's a secret"
+export REALM_SERVER_MATRIX_USERNAME=realm_server
+export ENABLE_FILE_WATCHER=true
+
+# ── Postgres is already running via docker-compose ──
+
+# ── Make forwarded ports public so the S3 preview can reach them ──
+echo "==> Making forwarded ports public..."
+gh codespace ports visibility 4201:public 4206:public 8008:public -c "$CODESPACE_NAME" 2>/dev/null || true
+
+# ── Matrix/Synapse ──
+echo "==> Starting Matrix/Synapse..."
+(cd packages/matrix && MATRIX_URL=http://localhost:8008 pnpm assert-synapse-running) &
+SYNAPSE_PID=$!
+
+# ── SMTP (MailHog) ──
+echo "==> Starting SMTP server..."
+(cd packages/matrix && pnpm assert-smtp-running) &
+
+# ── Icons server ──
+echo "==> Starting icons server..."
+pnpm --dir=packages/realm-server run start:icons &
+
+# ── Prerender service ──
+echo "==> Starting prerender services..."
+pnpm --dir=packages/realm-server run start:prerender-dev &
+pnpm --dir=packages/realm-server run start:prerender-manager-dev &
+
+# ── Worker ──
+echo "==> Starting worker..."
+pnpm --dir=packages/realm-server run start:worker-development &
+
+# Wait for Synapse before starting the realm server
+wait $SYNAPSE_PID || true
+
+# ── Realm server ──
+echo "==> Starting realm server..."
+SKIP_EXPERIMENTS=true \
+SKIP_BOXEL_HOMEPAGE=true \
+SKIP_SUBMISSION=true \
+MATRIX_URL=http://localhost:8008 \
+  pnpm --dir=packages/realm-server ts-node \
+    --transpileOnly main \
+    --port=4201 \
+    --matrixURL=http://localhost:8008 \
+    --realmsRootPath=./realms/codespaces \
+    --prerendererUrl=http://localhost:4221 \
+    --migrateDB \
+    --workerManagerPort=4213 \
+    \
+    --path='../base' \
+    --username='base_realm' \
+    --fromUrl='https://cardstack.com/base/' \
+    --toUrl="${REALM_SERVER_URL}/base/" \
+    \
+    --path='../catalog-realm' \
+    --username='catalog_realm' \
+    --fromUrl='@cardstack/catalog/' \
+    --toUrl="${REALM_SERVER_URL}/catalog/" \
+    \
+    --path='../skills-realm/contents' \
+    --username='skills_realm' \
+    --fromUrl="${REALM_SERVER_URL}/skills/" \
+    --toUrl="${REALM_SERVER_URL}/skills/" \
+    \
+    --path='../catalog-new/contents' \
+    --username='catalog_new_realm' \
+    --fromUrl="${REALM_SERVER_URL}/catalog-new/" \
+    --toUrl="${REALM_SERVER_URL}/catalog-new/" &
+REALM_PID=$!
+
+# ── Wait for realm server readiness ──
+echo "==> Waiting for realm server to be ready..."
+timeout 300 bash -c \
+  'until curl -sf "http://localhost:4201/_readiness-check?acceptHeader=application%2Fvnd.api%2Bjson" >/dev/null 2>&1; do sleep 2; done' \
+  || echo "Warning: realm server readiness check timed out after 5 minutes"
+
+# ── Trigger host preview build via GitHub Actions ──
+echo "==> Triggering host preview build pointed at this Codespace..."
+BRANCH_NAME="$(git rev-parse --abbrev-ref HEAD)"
+gh workflow run codespaces-preview.yml \
+  --ref "$BRANCH_NAME" \
+  -f codespace_name="$CODESPACE_NAME" \
+  -f realm_server_url="$REALM_SERVER_URL" \
+  -f matrix_url="$MATRIX_URL" \
+  -f icons_url="$ICONS_URL" \
+  || echo "Warning: could not trigger preview build. Run manually with: gh workflow run codespaces-preview.yml"
+
+echo ""
+echo "============================================"
+echo "  Backend services running!"
+echo ""
+echo "  Realm server:  ${REALM_SERVER_URL}"
+echo "  Matrix:        ${MATRIX_URL}"
+echo "  Icons:         ${ICONS_URL}"
+echo ""
+echo "  Host preview build triggered — check the"
+echo "  PR for a preview link once it completes."
+echo "============================================"
+
+# Keep the script alive
+wait
diff --git a/.github/workflows/codespaces-preview.yml b/.github/workflows/codespaces-preview.yml
new file mode 100644
index 0000000000..e8d9deee1c
--- /dev/null
+++ b/.github/workflows/codespaces-preview.yml
@@ -0,0 +1,106 @@
+name: Codespaces Preview
+
+on:
+  workflow_dispatch:
+    inputs:
+      codespace_name:
+        description: "Codespace name (used to derive forwarded port URLs)"
+        required: true
+        type: string
+      realm_server_url:
+        description: "Codespace realm server URL (e.g. https://<name>-4201.app.github.dev)"
+        required: true
+        type: string
+      matrix_url:
+        description: "Codespace Matrix URL (e.g. https://<name>-8008.app.github.dev)"
+        required: true
+        type: string
+      icons_url:
+        description: "Codespace icons URL (e.g. https://<name>-4206.app.github.dev)"
+        required: true
+        type: string
+
+permissions:
+  contents: read
+  issues: write
+  checks: write
+  pull-requests: write
+  id-token: write
+  statuses: write
+
+jobs:
+  deploy-codespaces-preview:
+    name: Build and deploy host preview for Codespaces
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # 4.2.2
+
+      - uses: ./.github/actions/init
+
+      - name: Configure AWS credentials
+        uses: aws-actions/configure-aws-credentials@ececac1a45f3b08a01d2dd070d28d111c5fe6722 # 4.1.0
+        with:
+          role-to-assume: arn:aws:iam::680542703984:role/boxel-host
+          aws-region: us-east-1
+
+      - name: Set environment variables for Codespaces backend
+        shell: bash
+        run: |
+          # Point the host build at the Codespace's backend services
+          echo "REALM_SERVER_DOMAIN=${{ inputs.realm_server_url }}/" >> $GITHUB_ENV
+          echo "RESOLVED_BASE_REALM_URL=${{ inputs.realm_server_url }}/base/" >> $GITHUB_ENV
+          echo "RESOLVED_CATALOG_REALM_URL=${{ inputs.realm_server_url }}/catalog/" >> $GITHUB_ENV
+          echo "RESOLVED_NEW_CATALOG_REALM_URL=${{ inputs.realm_server_url }}/catalog-new/" >> $GITHUB_ENV
+          echo "RESOLVED_SKILLS_REALM_URL=${{ inputs.realm_server_url }}/skills/" >> $GITHUB_ENV
+          echo "MATRIX_URL=${{ inputs.matrix_url }}" >> $GITHUB_ENV
+          echo "MATRIX_SERVER_NAME=localhost" >> $GITHUB_ENV
+          echo "ICONS_URL=${{ inputs.icons_url }}" >> $GITHUB_ENV
+
+      - name: Set PR branch name for S3 prefix
+        shell: bash
+        run: |
+          RAW_BRANCH="${GITHUB_REF_NAME}"
+          echo "PR_BRANCH_NAME=$(echo "${RAW_BRANCH}" | tr _ - | tr '[:upper:]' '[:lower:]' | sed -e 's/-$//' | sed -e 's/[^a-z0-9\-]//g' | cut -c1-60)" >> $GITHUB_ENV
+
+      - name: Build and deploy preview
+        shell: bash
+        env:
+          S3_PREVIEW_BUCKET_NAME: boxel-host-preview.stack.cards
+          AWS_S3_BUCKET: boxel-host-preview.stack.cards
+          AWS_REGION: us-east-1
+          AWS_CLOUDFRONT_DISTRIBUTION: EU4RGLH4EOCHJ
+        run: pnpm deploy:boxel-host:preview-staging
+
+      - name: Store preview URL
+        shell: bash
+        run: echo "PREVIEW_HOST=https://${PR_BRANCH_NAME}.boxel-host-preview.stack.cards/" >> $GITHUB_ENV
+
+      - name: Post status check with preview link
+        shell: bash
+        env:
+          GITHUB_TOKEN: ${{ github.token }}
+          REPOSITORY: ${{ github.repository }}
+          HEAD_SHA: ${{ github.sha }}
+        run: |
+          curl \
+            -X POST \
+            -H "Authorization: token $GITHUB_TOKEN" \
+            -H "Accept: application/vnd.github.v3+json" \
+            "https://api.github.com/repos/$REPOSITORY/statuses/$HEAD_SHA" \
+            -d '{"context":"Preview boxel-host codespaces","description":"Host preview connected to Codespace backend","target_url":"'"$PREVIEW_HOST"'","state":"success"}'
+
+      - name: Find associated PR and comment
+        shell: bash
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          PR_NUMBER=$(gh pr list --head "${GITHUB_REF_NAME}" --json number --jq '.[0].number' 2>/dev/null || true)
+          if [ -n "$PR_NUMBER" ]; then
+            gh pr comment "$PR_NUMBER" --body "### Codespaces Preview
+
+          - [Host preview (connected to Codespace)]($PREVIEW_HOST)
+          - Realm server: ${{ inputs.realm_server_url }}
+          - Matrix: ${{ inputs.matrix_url }}
+
+          > This preview build is connected to the Codespace \`${{ inputs.codespace_name }}\`. The preview will stop working when the Codespace is stopped."
+          fi
diff --git a/packages/host/config/codespaces.env b/packages/host/config/codespaces.env
new file mode 100644
index 0000000000..8daa202746
--- /dev/null
+++ b/packages/host/config/codespaces.env
@@ -0,0 +1,10 @@
+# These values are overridden at build time by the codespaces-preview workflow.
+# They serve as documentation of what's needed.
+REALM_SERVER_DOMAIN=http://localhost:4201/
+RESOLVED_BASE_REALM_URL=http://localhost:4201/base/
+RESOLVED_CATALOG_REALM_URL=http://localhost:4201/catalog/
+RESOLVED_NEW_CATALOG_REALM_URL=http://localhost:4201/catalog-new/
+RESOLVED_SKILLS_REALM_URL=http://localhost:4201/skills/
+MATRIX_URL=http://localhost:8008
+MATRIX_SERVER_NAME=localhost
+ICONS_URL=http://localhost:4206